// let 变量名:数据类型=值
//string number boolean null  undefined  symbol

let msg:string = 'hello';

let num:number = 123;

num = 12.00;

let isLogin:boolean = true;

let value:null = null;

let getVal:undefined = undefined;

//类型推断
let str = '123';

//联合声明

let msg1:string|number = 'hello';
// msg1 = true;

//any:任意类型

let msg2:any = 12;

msg2 = '122';

msg2 = true;

//mvvm ts环境搭建  变量声明
